The present invention relates to wooden trusses used for supporting structural loads and to hardware used in constructing wooden trusses which enhances the ease of installation and increases the resultant structural ridigity of the installed trusses for bearing structural loads.
In constructing various types of wooden trauss assemblies, inlcuding both roof trusses and floor joists, it has been common to use large wooden structural members such as 2" by 10"s. Such large wooden members, however, are becoming increasingly difficult to obtain and have increased substantially in cost. Consequently various alternatives have been sought for enabling the construction of trusses which are able to bear the structural loads of full dimension lumber but which are constructed from smaller pieces of dimension lumber such as 2".times.4" members which are spaced apart by metal connectors.
Substitutes for full dimension lumber roof trusses and floor joists must satisfy two primary criteria. First, the trusses must be able to withstand large compressive loads so that they may be used for bearing substantial structural loads. Secondly, it is desirable that the trausses be prefabricated at a manufacturing plant at a low labor cost and shipped to a building site without a high degree of risk of incurring damage to the trusses.
Various types of hardware have been developed for making prefabricated trusses. U.S. Pat. Nos. 3,025,577, to Jureit, 3,298,151 to Jureit, 3,503,173 to Jureit, 4,078,352 to Knowles and 4,348,850 to Reeder et al. and the U.S. patent application Ser. No. 337,671, field Sept. 24, 1982 and entitled TRUSS STRUCTURES CONSTRUCTED WITH METAL WEB MEMBERS, which is assigned to the assignee of the present invention, are representative of metal connectors which have been used for manufacturing trusses from smaller dimension lumber such as 2".times.4" s. Said patent application Ser. No. 337,671 is hereby incorporated by reference.
The latter of the noted Jureit patents (U.S. Pat. No. 3,503,173) discloses a metal strut member formed from a sheet metal plate for interconnecting top and bottom wooden chords where the strut member can have side longitudinally extending flanges and locating tabs stamped out of the ends of the plate.
The Knowles patent discloses a truss web structure with legs having pairs of longitudinally extending flanges which project in the same direction as teeth stricken from connectors located at each end on the web and at its apex and a longitudinally extending rib which projects in a direction opposite the direction of projection of the teeth. The Reeder et al. patent also discloses a web member for constructing truss structures with each leg of the web member having a pair of longitudinally extending flanges and locating tabs arranged at the ends of such flanges for arranging the web member on the wooden chord members.
The aforementioned U.S. patent application Ser. No. 337,671 discloses a metal web member with two legs and connecting plates disposed at the apex of the web member where the legs intersect and at the opposite end of each leg. The connecting plates each have a plurality of sharp projections extending generally perpendicular from the connecting plates. All of the connecting plates are disposed in the same plane. Each of the legs has at least one groove extending from the same side as the sharp projections of the connecting plates and extending substantially the entire length of the leg between the connecting plates. This groove is deeper in the proximity of the connecting plates than at the center of the leg midway between the connecting plates. On each of the legs, there is a pair of side flanges attached to and projecting from both outside edges of the leg and extending in the same direction as the groove in such leg. The depth of the side flanges varies throughout their length with the smallest depth being in the proximity of the connecting plates and the greatest depth being in the proximity of the midpoint of the flanges located between the connecting plates.
Attachment members have been marketed for connecting together the spaced apart wooden members which are used for constructing trusses. These attachment members have first and second connecting plates disposed at opposite ends of an intermediate leg which extends transversely between the ends of the spaced apart first and second wooden members of the truss. The intermediate leg of the aforementioned attachment members contains a plurality of parallel adjacent ridges of substantially constant cross-sectional shape and size which project outward away from the direction that the sharp projections in the connecting plates project when ingaging the spaced apart first and second wooden members of the truss.